A two hour hyperglycemic clamp experiment in which plasma glucose concentration is raised to 200 mg/dl are being carried out on female rhesus monkeys. These studies are performed twice on each animal. The first clamp experiment is being done while the animals are pregnant at approximately 150 days gestation. Approximately sixty days post-partum the animals undergo a second clamp experiment. Insulin concentration changes in response to the glucose infusion can be used to assess beta cell insulin secretion capacity. These studies are a follow-up to previous studies that indicated that insulin secretion in pregnant animals that had been exposed to chronic hyperinsulinemia in utero had impaired insulin secretion during pregnancy. Laboratory studies are in progress and sufficient data is not